Unfortunately a satisfying philosophy did not emerge to take the place of the departing devotion—which though of no great moral worth had possessed a certain constraining influence. The soundest Greek philosophy was itself out of date at home and was nowhere taught abroad. Plato’s great faith in ratiocination had created a highly imaged idealism of exceedingly great beauty—moral as well as aesthetic. But it had not withstood the prying curiosity of his sophisticated Greek pupils. Aristotle, afraid of the imagination, had set out almost at once to build science upon a foundation of careful and minute observation before trusting to imagination again. Epicurus, without sufficient equipment in science but stirred by a healthy respect for nature, had evolved a materialistic system on the theories of Democritus and Leucippus, which assumed an evolutionary process of creation without divine intervention. The system was attractive, but so full of inconsistencies and untested hypotheses that it led the shrewder young men of Athens into complete agnosticism. Those who were inclined to mysticism took refuge in Zeno’s equally facile pantheism. By the time the Romans were ready to delve into metaphysics, the logical flaws in all systems had been pointed out by the Greeks themselves. The world of thought was in confusion. Men had lost faith in their power to solve the riddle of the universe. Professional philosophers were quarrelling, and the rest were turning away in dismay to nearer tasks.